To everyone, please take a look at the following as I have tried to provide as much detail as possible; as I am at my wits end. I own a 1998 A6 Quarto with close to 200,000 km on it. Over the past couple of months, I have been having an engine mis-firing issue. I start the car, after about a minute the engine light starts going off and on and the car runs very rough for about a minute. As mentioned this is about a minute after starting, this is when the engine drops its rpms from around 1200 to 1000. Then after about 30 seconds of rough running the engine starts running okay and the engine light just stays on. At the same time, when I begin to drive the engine has to rev quite high (over 3000rpms) for the transmission to switch gears (usually I, flipped it over to tiptronic and do the shifting myself when this occurs; and this works.) Okay so here’s what I have replace, with limited success. New plugs, new wires, a new coil, a new MAF, a new temperature censor, and a can of fuel injector cleaner. Each one seems to correct the problem for about a day or even less and then it starts up again. Now, I had the plugs replace a second time, just the other day. And afterwards the car ran like a dream. No engine light and the transmission shifted at the correct rpms. However, this morning it was still cold but a lot damper then yesterday (I live just outside of Toronto, Canada) and the issue came back. (This is where I finally noticed the link between the mis-fire and the transmission). As mentioned the engine mis-fire goes away within 30 seconds and the transmission starts to work correctly after I get off the highway (its about a 30 minute drive – average speed is about 100km/hr, as the traffic is quite light). So here’s where I need your help. Is there any electronic component that is known to be faulty with condensation, as has something to do with the engines rpms, mis-firing and transmission? Last thing, I have had my mechanic do all of the work and also used his code reader. However about a week ago I went to my locate Audi dealership to have them put it on their diagnostic machine. And they were able to tell me that the engine is mis-firing but nothing more or the reason why. Also my mechanic keep the car in his heated shop over night, and the next morning the car was really hard to start and when it did, a lot of black smoke and the smell of gas was left behind. Any ideas would be appreciated...thanks.

 

Instead of throwing parts at it have the car VAG'd and find out what codes it has stored. Autozone will scan for free or search the forms and find out who has one locally.
Sounds like cats are bad.

 

Thanks AQ6

As my knowledge of car's is a bit week can you give me a bit more info in regards to your rely. VAG'd codes are these the same as the ones that my mechanic would have or the ones that Audi uses, as the reason why I replace the items mentioned was due to the codes that their units indicated. However if VAG'd id different can you give me a bit more details. Also "cats", does this mean the catalytic converters or something else... and if it is the Catalytic converters, why would this have this type of effect. I thought there purpose was to clean the exhaust, or do they provide an additional function.

Thanks

 

Sorry mde I should have read your post more carefully. VAG'd is a diagnostic tool to read the codes, and you have done that. It might be helpful if you have the vehicle scanned again and post the results.You can search the forum for those codes, it might give you a clue on what is going on. You might want to use the search function to look for post that have had similar conditions and how they resolved them. Cats do refer to catalytic converters. My thinking, and I'm not an expert, is that if the engine has been misfiring it might have damaged the catalytic converters. I would think that a scan would indicate this. What has your mechanic determined to be the problem? If he doesn't have experience with Audis it might be time for a new mechanic. I hope this helps, let us know how you make out. Good luck